Many various kinds of network applications have arisen due to rapid development of network techniques. For preventing sensitive personal information from being disclosed on an open and insecure network, it is necessary to provide some appropriate secure protocols. Concerning secure protocols, key agreement and authentication between user and server are paramount. In 2010, Cui and Cao proposed a secure anonymous key agreement for distributed networks, in which users collect other identities to utilize in communication so attackers cannot determine the real identity of the user. However, this protocol suffers the drawback of high calculation requirements.